Updated build environment for drone

Dockerfile

@@ -0,0 +1,18 @@
+FROM golang:alpine AS build-env
+
+ADD . /src
+RUN cd /src && go get -d && go build -o godns
+
+FROM alpine
+
+MAINTAINER Tyler Stuyfzand <tyler@tystuyfzand.com>
+
+EXPOSE 53
+
+RUN apk --no-cache add tini
+ENTRYPOINT ["/sbin/tini", "-g", "--"]
+CMD ["godns"]
+
+COPY etc/godns.example.conf /etc/godns.conf
+COPY --from=build-env /src/godns /usr/local/bin/godns
+RUN chmod +x /usr/local/bin/godns